<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        *{
            margin: 0;
            padding: 0;
        }
        #wrap{
            width: 600px;
            height: 100px;
            border: 1px solid;

            position: absolute;
            left: 0;
            right: 0;
            top: 0;
            bottom: 0;
            margin: auto;

            display: flex;
        }
        .item{
            border: 1px solid;
            background: pink;
            box-sizing: border-box;

            text-align: center;
            line-height: 100px;

            /*flex-basis: 0%;*/
        }
    </style>
</head>
<body>
    <div id="wrap">
        <div class="item" style="flex: 3">11</div>
        <div class="item" style="flex: 3">22222222</div>
        <div class="item" style="flex: 3">33333333333</div>
    </div>
</body>
</html>